Method and apparatus for forming tubes from sheet material



1949 D. c. THOMPSON 2,490,930

METHOD AND APPARATUS FOR FORMING TUBES FROM SHEET MATERIAL Filed Aug. 2a, 1946 /2 4 INVENTOR.

DONALD 6. THOMPSON f zm/rwg Patented Dec. 13, 1949 METHOD AND APPARATUS FOR FORMING TUBES FROM SHEET MATERIAL Donald- Thompson, Roanoke, Va., assignor to I v American Viscose Corporation, Wilmington, -Del., a corporation of Delaware i Application August 2a, 1946, Serial No". 693,543

- 1 This invention relates to tus for the production of tubular material from sheet material. In general, the objects of the invention are accomplished by overlapping the edges of a continuous sheet material preferably of indefinite length while introducing an adhesive material between the overlapped edges, thereafter pressing the overlapped edges to obtain effective adhesion therebetween, and then passing the tube in an upwardly inclined path. As the tube passes through the upwardly inclined path; a floating object, such as a flat disc, rides within the tube and prevents any adhesion, of it ruptures any adhered portions, between the overlapped joint of the edges and, the opposite wall of the tube.

In the drawing, illustrative of the invention- Figure 1 is a perspective view of a preferred embodiment, and j Figure 2 is a side elevation looking in the direction of the arrow A of Figure 1.

As shown in the drawing,a continuous sheet of material 2, such as of paper, cellophane, flexible plastic, etc., is carried upon a supply reel 3 having an axis 4 rotatably mounted in suitable bearings 5 carried by the supporting framework 6 upon a base, such as a floor, table top, or bench top I. As shown, the sheet passes downwardly behind two rods 8 which slope downwardly and toward each other along the upper portion of their lengths and then terminate in a U-shaped portion having approximately vertically inclined lengths 9 and a horizontally extending length l0. As the sheet passes under the horizontal part II), it is deflected thereabout, such as to a roughly horizontal plane and the lateral strips H of the material are bent inwardly toward each other under parts 8 and around parts 9. The lateral strips are of suflicient Width that their edges overlap at their point of complete convergence and such overlapping is controlled by the guiding rods 12 and I3 respectively. As shown, the lateral strip H furthest from the observer of Figure 1, passes under both of guide rods l2 and I3, whereas the other lateral strip ll closer to the'observer of Figure 1, passes over the extreme end portion of rod l2 and under rod Hi. This folding structure comprising rods, 8, l2 and I3 is generally conventional and may be replaced by any other equivalent folding means.

As will be observed in Figure 1,,the result is to produce a flattened tube with the lateral edges of the sheet 2 overlapped along an'intermediate area above the bottom wall of the tube, that is, the

central strip of the original sheet. This flattened tube structure proceeds over a transverse block l4 under two overhanging guide plates 15 secured methods and appara-' 8 Claims. (Cl. 93-82.)

J, jadiacent the edges of the folded structure. The

structure then passes under the roll IE, but before passing under roll IS, an adhesive material is applied between the overlapped edges of the sheet. As shown specifically, the adhesive material may be directed to this area between the over-' lapped edges by means of the tube 11. This tube I! is of arcuate form, the upper reach being supported at I8 upon a cross bar IQ of the framework and the lower reach thereof'having a discharge rv opening20 disposed between the overlapped edges and discharging inapprox'imate alignment with" the direction of travel of the overlapped edges. Any adhesive material in-liquiu or pulverized; solid form may be supplied to the upper mouth of the tube H, or the adhesive material may be in I the form-of a potentially adhesive but non-tacky strand of thermoplastic material. As shown, such a continuous strand 2| carried on a supply spool 22 rotatably mounted on a cross shaft 23 carried by the framework is introduced into the tube l1 and is drawn continuously from the discharge opening 20 by the traveling motion of the tube.

From roll l6, the flattened tube with the adhesive material disposed between the overlapped edges proceeds to a heating device 24 which may comprisea set of three rotatable rolls 25, 26, and 21, preferably idly mounted upon shafts carried in suitable bearings in the blocks 28. Any one or all of the rolls 25, 2'6 and 21 may be internally heated, such as by means of an electric heater element or an infra-red ray lamp 29 which may be supplied with electric current through a conduit 29a extending through a hollow bore in the roller shaft. A unit 29b 01 any conventional type may be connected in the conduit 29a to enable the control and adjustment of the heating element to provide constant temperature conditions. The several rolls 25, 26 and 2'! may have their axes spaced sumciently closely to provide a tight pressure nip through which the folded tube structure I is drawn. Preferably, however, the nip may be quite wide so that it does not of itself exert pressure upon the tube structure but pressure is de-. rived from the drawing of .the tube through the reversely bent arcuate p'ath about the several rollers. The pressure may be adjusted by controlling the relative position and size of the several rolls to obtain whatever necessary to eiiect proper adhesion for any particular adhesive employed.

Generally, nip pressure is not required, the pulling From the heating device 24, the flattened tube is drawn through an upwardly inclined path as at 25a. The travel through such inclined path may be controlled by a suitable guide roll (in advance of drawin rolls) disposed above the heating device 24, but a drawing device comprising a pair of nip rolls 30 and 3! is shown for this purpose. Ultimately, the flattened fabric leaving the drawing device may be passed to a device for collecting it in a continuous windin or it may be passed to a cutting means for severing it into short lengths, after which the severed lengths may be stacked or sent to further stages of operation or use.

As the flattened tube passes through the inclined path 25, a relatively flat object 32 floats freely therewithin and serves to sever any .adhesions between the seam or joint and the opposite wall of the tube. This floating object is preferably in the form of a disc having smooth rounded edges. The angle of inclination of the path 25 is not critical, since it may vary depending upon the tenacity of the particular adhesive employed under the conditions present immediately following the heating device 24. It is preferable to have the inclined path extending immediately above the heating device 24, so that the adhesions desired to be ruptured are not too rigidly set at this shape. When a thermoplastic strand is employed, it should be noted that any adhesions between the seam and the opposite wall of the tube are still in a thermoplastic condition as they pass into proximity with the disc 32, insuflicient cooling being available in the embodiment shown.

As stated hereinabove, any adhesive material in liquid form may be supplied to the tube ll. Examples of suitable adhesives are ordinary glue which sets upon heating or drying without heat; tacky resinous adhesives which harden upon heating or standing to effect removal of solvent; or dispersions of thermoplastic materials which require plasticization and solvent removal by heating. Instead of a liquid suspension or dispersion, powdered thermoplastic materials may be applied. Distribution from the tube" may be facilitated by subjecting the tube I! to vibrations. When a strand such as strand 2| is used, the strand may be formed of any thermoplastic or thermosetting material in thermoplastic condition. For example, a vinyl resin, e. g. Vinyon, polyethylene, polyvinyl chloride, or a partially condensed urea-formaldehyde or phenol formaldehyde resin in the form of a filament, yarn, plied thread, or the like may be used.

The introduction of the adhesive material in the form of a continuous strand has the advantage of facilitating continuous application of a uniform quantity without requiring special control methods and equipment and without involving sloppy conditions of application.

Changes and modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. A method of forming a tube from a sheet comprising the steps of continuously forwarding the sheet through a path, continuously forming a flattened tubular structure by overlapping the edges of the sheet at a point intermediate of the edges of the flattened structure, introducing an adhesive material between the overlapped edges, subjecting the flattened structure with the opposite walls in contact to heat and pressure to cause the adhesive material to join the edges, and thereafter directing the heated structure before the adhesive is rigidly set through an upwardly inclined path about a freely floating object contained within the structure whereby said object separates the joined wall from the opposite wall of the structure.

2. A method of forming a tube from a sheet comprising the steps of forwarding the sheet through a path, forming the sheet into a flattened tubular structure by overlapping the edges of the sheet at a point intermediate of the edges of the flattened structure, continuously introducing a potentially adhesive strand between the overlapped edges, subjecting the flattened structure with the opposite walls in contact and with the strand between the edges to heat and pressure to render the strand tacky and to join the edges, and then passing the structure while in a, heated condition and before the adhesive is rigidly set along an upwardly inclined path about an object floating freely within the tube whereby said object separates the joined wall from the opposite wall of the tube.

3. A method of forming a tube from a sheet comprising continuously forwarding the sheet through a path, folding the sheet into a flattened tubular structure by overlapping the edges of the sheet at a point intermediate of the edges of the flattened structure, guiding a strand of adhesive material between the overlapped edges, passing the flattened structure with the opposite walls in contact and with the strand therebetween through an arcuate path while subjecting it to heat and pressure therealong thereby joining the edges, and immediately thereafter passing the structure before the adhesive is rigidly set through an upwardly inclined path with an object floating freely within said structure and separating the joined wall from the opposite wall of the structure.

4. In combination, a supply for a continuous sheet of material, means for folding the sheet into a flattened tubular structure with its edges overlapped at a point intermediate of the edges of the flattened structure, means for introducing an adhesive material between the overlapped edges, means beyond the folding means and the introducing means for heating the flattened structure with the opposite walls in contact, means for guiding the material from the heating means through an upwardly inclined path, and means floating freely within the tube in the upwardly inclined path for separating the overlapped wall of the tubular structure from the opposite wall thereof.

5. In combination, supply means for a continuous sheet material, means for folding the sheet into a flattened tubular structure with its edges overlapped at a point intermediate of the edges of the flattened structure, means for introducing adhesive material between theoverlapped edges, a plurality of heating rolls about which the flattened tubular structure is passed, guiding means disposed above the heating rolls for drawing the, structure from the rolls through an upwardly in-- clined path and an object freely floatingly disposed within the structure between the heating means and the guiding means.

6. In combination, supply means for a continuous sheet material, means for folding the sheet into a flattened tubular structure with its edges overlapped at a point intermediate of the edges of the flattened structure, means for introducing adhesive material between the overlapped edges,

the structure between the heating means and the drawing means.

7. In combination, means for supplying a continuous sheet material, means for supplying a continuous strand of adhesive material, means for folding the sheet into a flattened tubular structure with its edges overlapped at a point intermediate of the edges of the flattened structure, means for guiding the strand from the supply thereof between the overlapped edges of the structure, means beyond such guiding means for heating the structure with the opposite walls in contact, means above the heating means for directing the structure from the heating means through an upwardly inclined path, and an object adapted to be freely floatingly carried within,

the structure between the heating means and the directing means.

8. In combination, means for supplying a continuous sheet material, means for supplying a continuous strand of thermoplastic material, means for folding the sheet material into a fiattened tubular structure with its edges overlapped at a point intermediate of the edges of the flattened structure, means for guiding the strand from the supply thereof into the space between the overlapped edges of the structure, a plurality of rolls about which the structure is adapted to be passed with the opposite walls in contact, heating means in at least one of said rolls, drawing means above said rolls for directing the structure through an upwardly inclined path from the heating means, and a flat disc freely fioatingly carried within the structure as it passes from the heating means to the drawing means.

DONALD C. THOMPSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES IPATENTS Germany Jan. 19, 1940 

